<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box img {
            animation: scale_b 3s linear infinite alternate;
        }

        @keyframes scale_b {
            0% {
                transform: scale(1);
            }

            50% {
                transform: scale(1.5);
            }

            100% {
                transform: scale(2);
            }
        }
    </style>
</head>

<body>
    <div class="box">
        <img src="../img/1.jpg" alt="">
    </div>
</body>

</html>